tests: consolidate docs presubmits (#16628)

Fixes #16625

Author: parthea

.github/workflows/docs.yml

@@ -13,66 +13,7 @@ permissions:
   contents: read
 
 jobs:
-  # The two jobs "docs" and "docsfx" are marked as required checks
-  # (and reset as such periodically) elsewhere in our
-  # automation. Since we don't want to block non-release PRs on docs
-  # failures, we want these checks to always show up as succeeded for
-  # those PRs. For release PRs, we do want the checks to run and block
-  # merge on failure.
-  #
-  # We accomplish this by using an "if:" conditional. Jobs
-  # thus skipped via a conditional (i.e. a false condition) show as
-  # having succeeded. See:
-  # https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/collaborating-on-repositories-with-code-quality-features/troubleshooting-required-status-checks#handling-skipped-but-required-checks
-  #
-  # Since we want advance notice of docs errors, we also have two
-  # corresponding non-required checks, the jobs "docs-warnings" and
-  # "docfx-warnings", that run for all non-release PRs (i.e., when the
-  # "docs" and "docfx" jobs don't run).
-  #
-  #
-  # PLEASE ENSURE THE FOLLOWING AT ALL TIMES:
-  #
-  # - the "*-warnings" checks remain NON-REQUIRED in the repo
-  #   settings.
-  #
-  # - the steps for the jobs "docs" and "docfx" are identical to the
-  #   ones in "docs-warnings" and "docfx-warnings", respectively.  We
-  #   will be able to avoid config duplication once GitHub actions
-  #   support YAML anchors (see
-  #   https://github.com/actions/runner/issues/1182)
   docs:
-    if: github.actor == 'release-please[bot]'
-    runs-on: ubuntu-latest
-    steps:
-    - name: Checkout
-      uses: actions/checkout@v6
-      # Use a fetch-depth of 2 to avoid error `fatal: origin/main...HEAD: no merge base`
-      # See https://github.com/googleapis/google-cloud-python/issues/12013
-      # and https://github.com/actions/checkout#checkout-head.
-      with:
-        fetch-depth: 2
-    - name: Setup Python
-      uses: actions/setup-python@v6
-      with:
-        python-version: "3.10"
-    - name: Install nox
-      run: |
-        python -m pip install --upgrade setuptools pip wheel
-        python -m pip install nox
-    - name: Run docs
-      env:
-        BUILD_TYPE: presubmit
-        TARGET_BRANCH: ${{ github.base_ref || github.event.merge_group.base_ref }}
-        TEST_TYPE: docs
-        # TODO(https://github.com/googleapis/google-cloud-python/issues/13775): Specify `PY_VERSION` rather than relying on the default python version of the nox session.
-        PY_VERSION: "unused"
-      run: |
-        ci/run_conditional_tests.sh
-  docs-warnings:    
-    if: github.actor != 'release-please[bot]'
-    name: "Docs warnings: will block release"
-    continue-on-error: true
     runs-on: ubuntu-latest
     steps:
     - name: Checkout
@@ -100,37 +41,6 @@ jobs:
       run: |
         ci/run_conditional_tests.sh
   docfx:
-    if: github.actor == 'release-please[bot]'
-    runs-on: ubuntu-latest
-    steps:
-    - name: Checkout
-      uses: actions/checkout@v6
-      # Use a fetch-depth of 2 to avoid error `fatal: origin/main...HEAD: no merge base`
-      # See https://github.com/googleapis/google-cloud-python/issues/12013
-      # and https://github.com/actions/checkout#checkout-head.
-      with:
-        fetch-depth: 2
-    - name: Setup Python
-      uses: actions/setup-python@v6
-      with:
-        python-version: "3.10"
-    - name: Install nox
-      run: |
-        python -m pip install --upgrade setuptools pip wheel
-        python -m pip install nox
-    - name: Run docfx
-      env:
-        BUILD_TYPE: presubmit
-        TARGET_BRANCH: ${{ github.base_ref || github.event.merge_group.base_ref }}
-        TEST_TYPE: docfx
-        # TODO(https://github.com/googleapis/google-cloud-python/issues/13775): Specify `PY_VERSION` rather than relying on the default python version of the nox session.
-        PY_VERSION: "unused"
-      run: |
-        ci/run_conditional_tests.sh
-  docfx-warnings:
-    if: github.actor != 'release-please[bot]'
-    name: "Docfx warnings: will block release"
-    continue-on-error: true
     runs-on: ubuntu-latest
     steps:
     - name: Checkout